I am used to being very active and now am off my feet with a stress fracture and sprained ankle. I have been doing abdominal, arms, and leg exercises while lying down, but am missing my running and cardio. What can I do to stay fit until I can get back on my feet?
You can still do resistance training with an emphasis on muscular endurance. That means low weights and high reps. This will transfer well into your cardio when you get back on your feet.